Mention RAPI client in documentation

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

doc/rapi.rst

@@ -136,6 +136,11 @@ Usage examples
 You can access the API using your favorite programming language as long
 as it supports network connections.
 
+Ganeti RAPI client
+++++++++++++++++++
+
+Ganeti includes a standalone RAPI client, ``lib/rapi/client.py``.
+
 Shell
 +++++
 

lib/rapi/client.py

@@ -21,6 +21,9 @@
 
 """Ganeti RAPI client."""
 
+# No Ganeti-specific modules should be imported. The RAPI client is supposed to
+# be standalone.
+
 import httplib
 import urllib2
 import logging